This report is intended to assist buyers of automated external defibrillators (AEDs). AEDs are portable, electronic medical devices used to treat cardiac arrest. These devices monitor the heart’s rhythm and advise the rescuer when a shock is required. AEDs are widely used by paramedics and police and are becoming commonly available in public places, such as office buildings, shopping malls, schools and airports. Manual external and implantable cardioverter defibrillator devices are excluded from this report.